Accessing functions stored in a table using luabind

[framebuffer]

Hello!

I have stored some functions in a lua table and i want to access them using C++. The script file is as follows:


-------------------------------------------------------------------------------

-- create the StateAcON state

-------------------------------------------------------------------------------
StateAcON = {}


StateAcON["Enter"] = function()

  print ("[Lua]: AC is turning on...")

end


StateAcON["Execute"] = function()

    print ("[Lua]: WOOSHHHHHHHHHHhhhhhh")

end

 
StateAcON["Exit"] = function()

  print ("[Lua]: AC is tuning off...")

end

The C++ code is listed below:

extern "C"
{
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
}

#include <iostream>
#include <luabind/luabind.hpp>

using namespace std;

int main()
{
    //create a lua state
    lua_State *pLua = lua_open();

    luaL_openlibs(pLua);

    //open luabind
    luabind::open(pLua);


    /* load and run the script here */
    if (int error = luaL_dofile(pLua, "script.lua") != 0)
    {
        // if there is an error on any of these functions it is left on top of the stack as a string.
        cout << lua_tostring(pLua, -1) << "\n";

        return 0;
    }

    // Luabind
    luabind::object states;
    states = luabind::globals(pLua);

    //states["StateAcON"]; ???
    //states["Execute"](); ???



    //tidy up
    lua_close(pLua);

    return 0;
}

I am not too sure how to proceed after we access the global lua state. Basically what I want to do is to access a function stored inside a lua table from within C++. First i need to access the table and then the function stored in it.

Thanks,
fb

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[framebuffer]

Hello Again!

I solved the problem using the following statement:

luabind::globals(pLua)["StateAcON"]["Execute"]();

But when I try to do this:

        luabind::object states;
        states = luabind::globals(pLua);
        states["StateAcON"]["Execute"]();

The script is executed fine, but the program crashes upon termination. The moment I assign the returned object from globals the program crashes upon termination after executing the script successfully.

The moment I comment the following line:

states = luabind::globals(pLua);

the crash vanishes. This happens irrespective of the following statement:

states["StateAcON"]["Execute"]();

The problem is an unhanded win32 exception at line 169 in ref.cpp (according to the debugger). This is the statement it breaks to:

lua_rawgeti(L, t, FREELIST_REF);

I have tried this in a minimalistic application. The moment I assign the object returned by globals to a local instance of object, the application runs fine but crashes upon exit.

On the contrary, using a nameless temporary works fine as I mentioned above.

Any ideas?

I tried this too but no luck (same result):

        luabind::object states;
        states = luabind::globals(pLua)["StateAcON"];
        luabind::object foo = states;
        states["Execute"]();

Thanks,
fb,

framebuffer wrote:

Hello!

I have stored some functions in a lua table and i want to access them using
C++. The script file is as follows:


-------------------------------------------------------------------------------

-- create the StateAcON state

-------------------------------------------------------------------------------
StateAcON = {}


StateAcON["Enter"] = function()

  print ("[Lua]: AC is turning on...")

end


StateAcON["Execute"] = function()

    print ("[Lua]: WOOSHHHHHHHHHHhhhhhh")

end


StateAcON["Exit"] = function()

  print ("[Lua]: AC is tuning off...")

end

The C++ code is listed below:

extern "C"
{
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
}

#include <iostream>
#include <luabind/luabind.hpp>

using namespace std;

int main()
{
    //create a lua state
    lua_State *pLua = lua_open();

    luaL_openlibs(pLua);

    //open luabind
    luabind::open(pLua);


    /* load and run the script here */
    if (int error = luaL_dofile(pLua, "script.lua") != 0)
    {
        // if there is an error on any of these functions it is left on top
of the stack as a string.
        cout << lua_tostring(pLua, -1) << "\n";

        return 0;
    }

    // Luabind
    luabind::object states;
    states = luabind::globals(pLua);

    //states["StateAcON"]; ???
    //states["Execute"](); ???



    //tidy up
    lua_close(pLua);

    return 0;
}

I am not too sure how to proceed after we access the global lua state.
Basically what I want to do is to access a function stored inside a lua
table from within C++. First i need to access the table and then the
function stored in it.

Thanks,
fb

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[James Porter-2]

Chances are, the problem is that the destructor for "states" is being called after you close the Lua state "pLua". The destructor calls some code from the Lua API, and if you've closed pLua already, you're going to get a pointer error. To get around this, I generally make instances of luabind::object pointers so I can manually delete them before I close the state (obviously not necessary if the luabind::object is short-lived).

- James

On 9/27/07, framebuffer <framebuffer@...> wrote:

Hello Again!

I solved the problem using the following statement:

luabind::globals(pLua)["StateAcON"]["Execute"]();

But when I try to do this:

        luabind::object states;
        states = luabind::globals(pLua);
        states["StateAcON"]["Execute"]();

The script is executed fine, but the program crashes upon termination. The
moment I assign the returned object from globals the program crashes upon
termination after executing the script successfully.

[snip]

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[framebuffer]

Dear James,

Thanks one more time for saving the day! The following solution worked great!

        luabind::object *pStates = new luabind::object;
        *pStates = luabind::globals(pLua);

        (*pStates)["StateAcON"]["Execute"]();

        delete pStates;

Thanks!
fb.

James Porter-2 wrote:

Chances are, the problem is that the destructor for "states" is being called
after you close the Lua state "pLua". The destructor calls some code from
the Lua API, and if you've closed pLua already, you're going to get a
pointer error. To get around this, I generally make instances of
luabind::object pointers so I can manually delete them before I close the
state (obviously not necessary if the luabind::object is short-lived).

- James

On 9/27/07, framebuffer <[e-mail]> wrote:
>
>
> Hello Again!
>
> I solved the problem using the following statement:
>
> luabind::globals(pLua)["StateAcON"]["Execute"]();
>
> But when I try to do this:
>
>         luabind::object states;
>         states = luabind::globals(pLua);
>         states["StateAcON"]["Execute"]();
>
> The script is executed fine, but the program crashes upon termination. The
> moment I assign the returned object from globals the program crashes upon
> termination after executing the script successfully.


[snip]

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